all recipes i have seen use ba and bb for standard recipes, but when people start making the strong mg/ml recipes that will usually crash, they use the eo and gua to prevent the crashing, for the pain some people are adding the bs. over at muscle discussion a very knowledgeable member named northern put a couple of these recipes to help members with their pip.
member northern from md posted this:"The solvents used can cause pain in 2 ways. Benzyl alcohol (BA) is used at 1%-2% as a preservative and antiseptic. If the alcohol content is too high the gear will burn. Pain in the first 24 hours is usually caused by heavy solvents, pain in the next few hours is usually cause by crystalization. Another way is a bad recipe. if someone used 2% BA, and the rest of the solution oil, the mg/mL would have to be low due to oil's weak ability to hold crystals. On the other hand, a recipe like 2% BA, 5% Guaiacol (super solvent), 10% Benzyl Salicylate (liquid asprin) with the filler split 50:50 between Ethyl Oleate (oil/solvent hybrid) and normal oil should be far less painful."
here is another post from northern with a recipe for 500mg test with bs for pain: 400mg/ml will hold just fine with straight GSO, BA and BB - If its Test E. If you want 500 I would try the following:
BA 2%
BB 20%
Benzyl Salicylate 10% - Make sure it is of good quality/purity
GSO or 50/50 EO/GSO - though not necessary unless you like thinner gear.
That would be a good place to start. THe problem you run into is there is only so much you can get into 1ml. So with 500mg of test per ml you have 1/2ml of straight hormone and 0.02ml of BA, 0.2 ml of BB, 0.1ml of BS and the remaining 0.18ml is oil. Compared to say test e @ 300mg which is closer to 0.48ml oil using 2/20 recipe.